This is a continuation of previous research experiments attempting to characterize the optimal laser source and transmitting optical fibers for intravascular precise microablative surgery. Over the past year, considerable additional work has helped to characterize the optimal lasing parameters for variable composition plaque ablation. In addition, substantive progress has been made in developing zirconium fluoride glass fibers to meet power transmission, flexibility, strength, and durability requirements. Catheter and fiber tip development is proceeding such that we have demonstrated high efficiency ablation of tissue in a wet field through flexible catheters using a 200 micron fiber filling a 1.5mm sapphire output window. These preliminary studies have demonstrated the feasibility of Er:YAG laser and zirconium fluoride fibers as a system for laser angioplasty.